The footage also shows train driver eating in his cabin before driving away.
"I know that I was wrong and I am devastated by what happened to that woman", Tonelli told Corriere.
The woman from Belarus was trying to leave the train at the last minute when her bag became caught. But he added that in the video, it can be seen that he looked twice in the mirror, so he was not reckless.
At the far end of the platform, Belorus national Natalya can be seen cautiously stepping on board before apparently changing her mind and getting off again.
The woman attempts to board the subway when the doors close on her bag.
The incident has raised safety questions about the trains in the city and some officials have said the failure of the sensors and emergency buttons mean the driver is not fully responsible for what happened.
The train driver, Francesco Compagna, is suspended and is under investigation.
Authorities in Rome are now investigating an incident that left a woman seriously injured.
Stefano Bottoni, national secretary of trade union Sul, said extra measures were needed to avoid a repeat of the accident.